Cloning Vectors and Competent Host

Introduction

Cloning vectors are special agents; they are mere carriers responsible for carrying the part of the desired gene inside the host cell. Once they are inside the host cell, these vectors can induce the host to activate their replication. In this way, the DNA inserted in the cloning vector also starts to replicate along with it. Once the optimal amount is replicated, the vector is released or removed, and the cloned DNA is taken to manufacture the biological product. 

Over time and development in biotechnology, there are many unique cloning vectors used in the DNA replication process. However, the most used cloning vector ever in the field is none other than the plasmids. Plasmids are not the primary genetic carrier of bacteria. Their round genetic chromosomal part of the DNA is not easily expressed during standard DNA cloning. The first-ever cloning was performed from the bacteria Escherichia coli. However, these days, cloning is based not only on naturally extracted vectors but also on the possibility of getting artificial vectors cloned quickly with the help of new techniques.

Features of a Cloning Vector

There are a few features to a cloning vector, and these features make or decide a cloning vector to be good or bad for users. The cloning vector must have all the necessary elements that are required for the propagation and replication of the DNA we are inserting into it. 

A Cloning Site

Plasmids are circular cloning vectors, and they are made up of numerous genes. But one cannot insert the required part of DNA to any site. The site of attachment of the foreign DNA into the plasmid is the cloning site. The first criteria of selecting a cloning vector are looking for a good cloning site for the action to happen. Different enzymes such as DNA ligase digest the DNA sequence present at the cloning site to open up the space for the upcoming DNA. One must also look at whether the cloning site is easily digestible with enzymes. If not, there could be numerous problems out there. 

Selectable Marker

As the name mentions, it is a marker used to differentiate between the transformants and non transformants. After the insertion of the required DNA, there is a chance that not all vectors will get inserted with the required  DNA. If we use a medium in which both cloned and cloning vectors are present, then the efficiency of the biological product decreases. Hence, selecting only the cloning vectors with the DNA of interest is always helpful. 

The Reporter Gene

The reporter gene, which is used in a few cloning vectors, is a gene that screens or monitors successful clones. 

Types of Cloning Vectors

There could be numerous types of cloning vectors depending on their extraction and work. Some of them are-

• Plasmid- Circular extrachromosomal DNA of a few bacteria. Plasmids have a high-frequency replication rate and have all the necessary features for being an ideal cloning vector; hence it is always preferred
• Bacteriophage- Bacteriophages are the viruses that infect different bacterias and inject them with their genetic constituents for replication. Biotechnology scientists exploit this bacteriophage feature; it is used as cloning vectors
• Cosmids- Cosmids are also basically modified plasmids, but they contain essential elements required for DNA to be packed inside

Competent Host

A competent host is a host that allows easy insertion of the cloning vector inside it and, on the other hand, produces positive results as required by the scientist.

To understand a competent host, you must understand the concept that DNA is a hydrophilic molecule. It is made of the bi lipid layer, and hence any particle that is not soluble in lipid cannot pass through the cell membrane. 

To enter DNA inside the required host, we need to make the DNA host cell competent. There ways by which such competent hosts are prepared.

Recombinant DNA can then be inserted into the cells by incubating the cells with the recombinant DNA on ice. Then the cells are placed at 42 degree celsius and then put again on ice.

Conclusion

Above in the article, we have mentioned cloning vectors and competent hosts.The features of the clonal vectors have been discussed that are used for biotechnology. Clonal vectors have a clonal site, reporter genes and selectable markers. Cosmids, bacteriophage and plasmids are vectors that are used in biotechnology.